The principal overall objectives are to elucidate the epidemiology of dengue virus in Malaysia, with special reference to the jungle cycle; and to establish the importance of the jungle cycle in relation to disease in man. These studies, which have established that dengue is a zoonosis involving wild monkeys in primary rain-forest in Malaysia, are continuing with intensive efforts to determine which mosquito species serves as the important jungle vector. A variety of collecting methods will be employed, including the use of monkey-baited mosquito traps. Laboratory studies will include isolation, characterization, and identification of viruses isolated and detailed serology utilizing mice and cell cultures, as well as colonization of jungle mosquitoes and experimental transmission attempts.